Huigobio exilicauda, Jiang, Zhong-Guan & Zhang, E., 2013

Jiang, Zhong-Guan & Zhang, E., 2013, Molecular evidence for taxonomic status of the gudgeon genus Huigobio Fang, 1938 (Teleostei: Cypriniformes), with a description of a new species from Guangdong Province, South China, Zootaxa 3731 (1), pp. 171-182 : 174-176

Huigobio exilicauda , new species

( Fig. 2 )

Holotype. IHB 76IV 7485, 65.8 mm SL; South China: Guangdong Province: Lianping County (approximately 114°28′ E, 24°22′ N): a tributary discharging into the Dong-Jiang of upper Pearl River basin; April 1976.

Paratypes. IHB 76IV 6929, 76IV 7483, 76IV 7490, 76IV 7499, 76IV 7501, 76IV 7583, 6 specimens, 56.1–71.1 mm SL; other data same as holotype.

Non-type materials. All specimens were secured in 1976 from the Pearl River basin in Guangdong Province, China. IHB 76IV 6228, 76IV 6232, 2 specimens, 54.4–67.3 mm SL; a tributary flowing into Bei-Jiang at Lechang City. IHB 76IV 7672, 1 specimen, 67.0 mm SL; a tributary flowing into the Dong-Jiang at Xinfeng County. IHB 76IV 6926, 76IV 6928, 2 specimens, 55.3–61.0 mm SL; a tributary flowing to the Dong-Jiang at Lianshan County. IHB 76IV 6799- 6801, 76IV 6803, 4 specimens, 50.2–56.8 mm SL; a tributary flowing to the Dong-Jiang at Lianzhou City. IHB 76IV 1003, 1 specimen, 55.2 mm SL; a tributary flowing into the Dong-Jiang at Heping County.

Diagnosis. Huigobio exilicauda is distinguished from H. chenhsienensis in having a slender (vs. stouter) caudal peduncle (depth 6.8–7.8 vs. 9.0–10.5 % of SL; length 17.1–19.5 vs. 13.9–16.3 % of SL); and a narrower (vs. greater) interorbital space than eye diameter, its width being 23.0–27.2 (vs. 28.5–37.4) % of HL.

Description. Morphometric data for seven type specimens and 10 non-type ones are given in Table 2 . See Figure 1 A for soft-tissue structures of the mouth and Figure 2 for general body appearance. Body elongate, anteriorly subcylindrical, and posteriorly compressed, with greatest body depth at dorsal-fin origin, and least caudal-peduncle depth immediately anterior to caudal-fin base. Dorsal body profile slightly convex or straight from snout tip to dorsal-fin origin; from there to caudal-fin base slightly concave. Ventral profile from snout tip to pectoral-fin insertion flat, from there to anal-fin origin convex then slightly concave from anal-fin origin to caudalfin base. Anus situated slightly nearer to pelvic-fin insertion than to anal-fin origin. Caudal peduncle slender and strongly compressed.

Head small, shorter than or approximately equal to body depth. Snout bluntly rounded when viewed laterally, with shallow transverse notch across tip in front of nostrils. Eye large, dorsolaterally positioned nearly in middle of head. Interorbital space slightly concave, narrow, width shorter than eye diameter. Nostrils nearer to anterior margin of eye than to tip of snout. Maxillary barbels rooted at base of external surface of confluence between upper and lower lips around corner of mouth, shorter than half eye diameter. Mouth inferior and transverse, its cleft bending slightly backward at corner of mouth.

Rostral fold simple and smooth, covering base of median portion of upper lip. Lips well-developed, and confluent around corners of mouth. Upper lip fimbriate or crenulated in median portion, and irregularly papillated on margin and inner surface of lateral portion. Papillae arranged in one row on median portion of upper lip, but in several rows on lateral portions. Lower lip modified into two lateral lobes and one central pad; two lateral lobes expanded posteriorly as a wing-like, more or less triangular, papillated flap, and connected posteromedially with each other, but not confluent. Central pad very small, fleshy, smooth, heart-shaped, and not bisected longitudinally by a groove. Upper and lower jaws exposed, especially lower one, with transverse cutting edges covered with horny sheaths.

Dorsal fin with 1 simple or unbranched and 7 (17) branched rays, last one split to base; origin nearer to snout tip than to caudal-fin base; distal margin straight. Pectoral fin with 1 simple and 10 (17) branched rays, longer than head; tip of adpressed fin extending beyond vertical through dorsal-fin origin, but not approaching pelvic-fin origin. Pelvic fin with 1 simple and 7 (17) branched rays, inserted below third or fourth branched dorsal-fin ray, usually closer to caudal-fin base than to snout tip; pelvic-fin insertion nearly equidistant from snout tip and caudalfin base. Anal fin with 3 simple and 5 (17) branched rays; tip of adpressed fin not reaching caudal-fin base; origin equidistant from pelvic-fin insertion and caudal-fin base; distal margin slightly convex. Caudal fin shallowlyforked, upper and lower lobes equal in length and shape.

Lateral line complete, extending along middle of flank. Lateral-line perforated scales 37 (6), 38 (9), or 39 (2). Scale rows above lateral line 3 1/2 (17) and below 2 1/2 (17). Predorsal scales 9 (17). Circumpeduncular scales 12 (17). Chest and belly between pectoral-fin base scaleless. Gas bladder reduced, anterior chamber enveloped in fibrous capsule, posterior chamber very small, stick-like. One row of pharyngeal teeth (IHB 76IV 7673, 70.12 mm SL); tooth pattern 5-5, with hooked and pointed tips.

Coloration in preservative. Body dorsally blackish, ventrally grayish-white. Top of head black; upper part of operculum with dark blotch. Longitudinal dark brown stripe, its width occupying about 2 scale rows, extending along lateral line covered with 7–8 vague black blotches. Scales above lateral line covered with dark chromatophores. 4 to 5 black crossbars on middle of dorsal region of body. Dorsal and caudal fins dusky, irregular spots scattered along branched rays. Other fins grey-white with fewer spots.

Distribution. Known from the Pearl River basin at Lianping County, Lianzhou City, Lechang City, Xinfeng County, Lianshan County, Heping County, Wengyuan County, and Shaoguan City, Guangdong Province, South China ( Fig. 3 ).

Etymology. The specific epithet, used as a noun, is made from a combination of the Latin word exilis (thin or slender) and cauda (tail), alluding to the presence of a slender caudal peduncle.

Remarks. This new species has until now been misidentified as H. chenhsienensis . Fang (1938) described H. chenhsienensis on the basis of a single specimen from Chenhsien (now Shengzhou City), Chekiang (now Zhejiang) Province, in the Cao’e-Jiang basin. It was later reported from coastal river basins in Zhejiang Province (Luo et al., 1977; Mao, 1989). Specimens of the Zhu-Jiang basin in Guangdong, Guangxi and Yunnan provinces were also recognized as H. chenhsienensis (Zheng & Yang, 1989; Pan et al., 1990; Yue, 1998; Wen, 2006; Du et al., 2008). The same species was reported from the lake Poyang system of the lower Chang-Jiang basin in Jiangxi Province (Zhang et al., 1996; Huang & Wu, 2010). Our observation showed that the specimens of the lake Poyang system of the lower Chang-Jiang basin in Jiangxi Province are conspecific with H. chenhsienensis , but those of the Zhu-Jiang basin in Guangdong and Guangxi provinces represent an undescribed species, here named H. exilicauda . Du et al. (2008) reported on the occurrence of H. chenhsienensis in the Tuoniang-Jiang, a tributary discharging into the You- Jiang of the Zhu-Jiang basin in Yunnan Province, South China. We have no access to Du et al.’s material in this study, but their figure depicts a species having two lateral lobes of the lower lip interrupted by a large central pad, and longer maxillary barbels. These two characters do not place it in Huigobio , as here defined, but in Microphysogobio .

Figures

FIGURE 1. Ventral view of oromandibular structures in: (A) Huigobio exilicauda, IHB 76 IV 6232, 66.7 mm SL; South China: Guangdong Province: a tributary of upper Pearl River at Lechang City; (B) Huigobio chenhsienensis, IHB 74 IX 4610, 79.4 mm SL; South China: Zhejiang Province: Ling-Jiang basin at Xianju County; (C) Microphysogobio nudiventris, IHB 2011040304, 64.7 mm SL; South China: Hubei Province: Du-He, a tributary flowing into the Han-Jiang basin at Zhushan County; (D) Platysmacheilus exiguus, IHB 87 V 057, 117.2 mm SL; South China: Guizhou Province: Qingshui-Jiang at Kaili City; (E) Pseudogobio vaillanti, IHB 81 VII 1308, 108.7 mm SL; South China: Henan Province: Bai-He basin at Xinye County; (F) Abbottina rivularis, IHB 77 VI 2736, 69.6 mm SL; West China: Gansu Province: Beida-He basin at Jiuquan City. Abbreviations: cp = central pad; lj = lower jaw; ll = lateral lobe of lower lip; rc = rostral cap; uj = upper jaw; ul = upper lip.

FIGURE 2. Huigobio exilicauda, IHB 76 IV 7485, holotype, 65.8 mm SL; China, Guangdong Province, Lianping County, tributary of upper Pearl River.

FIGURE 3. Map showing localities of Huigobio exilicauda examined. Black square = type locality; black circles = other collections.

Tables

TABLE 2. Morphometric data for Huigobio exilicauda and Huigobio chenhsienensis.

Characters	H. exilicauda (n = 17)	H. chenhsienensis (n = 29)
	Holotype Range (Mean ± SD)	Range (Mean ± SD)
SL (mm)	65.8 50.2–71.1(59.3 ± 5.95)	50.1–74.0 (62.9 ± 6.59)
In percentage of SL
Body depth	20.7 15.7–21.2 (18.6 ±1.63)	16.3–21.4 (19.5 ± 1.21)
Pre-dorsal length	41.2 40.2–46.0 (41.6 ± 1.33)	36.8–48.4 (44.6 ± 1.89)
Dorsal-fin base length	14.5 14.5–17.9 (15.7 ± 0.76)	14.7–17.5 (16.1 ± 0.66)
Dorsal-fin length	20.5 18.2–23.4 (20.9 ± 1.26)	16.7–24.4 (21.1 ± 1.47)
Pre-anal length	76.2 76.2–82.8 (78.1 ± 1.65)	70.4–82.0 (77.7 ± 2.31)
Anal-fin base length	6.1 5.2–6.6 (5.9 ± 0.43)	5.7–8.3 (7.0 ± 0.61)
Anal-fin length	15.9 14.7–18.3 (16.4 ± 1.02)	14.3–17.8 (16.2 ± 0.87)
Pre-pectoral length	21.8 20.8–22.9 (21.9 ± 0.73)	21.4–25.4 (22.9 ± 0.94)
Pectoral-fin base length	5.5 5.1–6.6 (5.9 ± 0.41)	5.5–8.3 (6.3 ± 0.57)
Pectoral-fin length	25.2 23.7–29.3 (25.6 ± 1.45)	20.1–26.4 (24.3 ± 1.15)
Pre-pelvic length	50.3 48.5–56.3 (51.1 ± 1.70)	50.2–54.4 (52.6 ± 1.20)
Pelvic-fin base length	5.0 4.8–5.6 (5.2 ± 0.24)	4.2–6.5 (5.2 ± 0.50)
Pelvic-fin length	20.7 18.2–24.5 (20.7 ± 1.47)	16.1–20.3 (18.9 ± 1.01)
Caudal peduncle length	17.3 17.1–19.5 (17.9 ± 0.73)	13.9–16.3 (15.1 ± 0.64)
Caudal peduncle depth	7.1 6.8–7.8 (7.4 ± 0.26)	9.0–10.5 (9.7 ± 0.47)
Head length	20.6 19.5–23.1 (21.2 ± 0.96)	19.6–24.4 (21.6 ± 0.94)
In percentage of HL
Head depth	68.7 58.8–70.7 (66.9 ± 3.20)	61.2–73.7 (66.9 ± 2.45)
Head width	73.0 64.1–76.4 (69.6 ± 3.60)	69.4–84.5 (74.9 ± 3.49)
Snout length	39.6 36.8–42.9 (40.4 ± 1.58)	33.7–45.5 (39.5 ± 2.48)
Eye diameter	27.8 25.8–34.6 (28.8 ± 2.22)	25.2–31.4 (27.2 ± 1.58)
Interorbital width	26.6 23.0–27.2 (24.8 ± 1.19)	28.5–37.4 (31.7 ± 2.16)
Mouth width	31.1 21.9–32.0 (28.3 ± 2.85)	23.7–38.8 (30.3 ± 4.21)